EP 3715493 A1 20200930 - HIGH STRENGTH STEEL SHEET AND METHOD FOR PRODUCING SAME
Title (en)
HIGH STRENGTH STEEL SHEET AND METHOD FOR PRODUCING SAME
Title (de)
HOCHFESTES STAHLBLECH UND VERFAHREN ZUR HERSTELLUNG DAVON
Title (fr)
TÔLE D'ACIER À HAUTE RÉSISTANCE ET SON PROCÉDÉ DE PRODUCTION
Publication
Application
Priority
- JP 2017251048 A 20171227
- JP 2018037569 W 20181009
Abstract (en)
An object of the present invention is to provide a high-strength steel sheet further excellent in both strength and workability and a method for producing the high-strength steel sheet.The high-strength steel sheet according to the present invention has a specific composition and a microstructure including lower bainite, martensite, retained austenite, upper bainite, and ferrite such that the total area fraction of the lower bainite, the martensite, and the retained austenite is 40% to 100%, the area fraction of the retained austenite is 15% or less, and the total area fraction of the upper bainite and the ferrite is 0% to 60%. In the microstructure, the area fraction of elongated ferrite phase grains having an aspect ratio of 3 or more is 1% or less, the average crystal grain size of martensite included in a region extending 50 µm from a surface of the steel sheet is 20 µm or less, the content of oxide particles having a minor axis length of 0.8 µm or less in the region extending 50 µm from the surface of the steel sheet is 1.0 × 10<sup>10</sup>particles/m<sup>2</sup>or more, and the content of coarse oxide particles having a minor axis length of more than 1 µm in the region extending 50 µm from the surface of the steel sheet is 1.0 × 10<sup>8</sup>particles/m<sup>2</sup>or less. The content of hydrogen trapped in the steel sheet is 0.05 ppm by mass or more.
IPC 8 full level
C22C 38/00 (2006.01); C21D 9/46 (2006.01); C22C 38/06 (2006.01); C22C 38/60 (2006.01)
CPC (source: EP KR US)
C21D 6/005 (2013.01 - EP); C21D 8/02 (2013.01 - EP); C21D 8/0205 (2013.01 - EP); C21D 8/0226 (2013.01 - EP KR US); C21D 8/0236 (2013.01 - EP KR US); C21D 8/0273 (2013.01 - KR US); C21D 9/46 (2013.01 - EP KR US); C22C 38/00 (2013.01 - EP); C22C 38/001 (2013.01 - EP); C22C 38/002 (2013.01 - EP); C22C 38/005 (2013.01 - EP); C22C 38/008 (2013.01 - EP US); C22C 38/02 (2013.01 - EP KR US); C22C 38/04 (2013.01 - EP KR US); C22C 38/06 (2013.01 - EP KR US); C22C 38/08 (2013.01 - EP); C22C 38/12 (2013.01 - EP); C22C 38/14 (2013.01 - EP); C22C 38/16 (2013.01 - EP); C22C 38/22 (2013.01 - EP); C22C 38/26 (2013.01 - EP); C22C 38/32 (2013.01 - EP); C22C 38/38 (2013.01 - EP); C22C 38/42 (2013.01 - KR US); C22C 38/44 (2013.01 - KR US); C22C 38/46 (2013.01 - KR US); C22C 38/48 (2013.01 - US); C22C 38/50 (2013.01 - US); C22C 38/60 (2013.01 - EP KR US); C23C 2/02 (2013.01 - EP US); C23C 2/0224 (2022.08 - EP KR US); C23C 2/024 (2022.08 - EP KR US); C23C 2/06 (2013.01 - EP KR); C23C 2/28 (2013.01 - EP US); C23C 2/29 (2022.08 - EP KR US); C23C 2/40 (2013.01 - EP KR US); C21D 2211/001 (2013.01 - KR US); C21D 2211/002 (2013.01 - KR US); C21D 2211/005 (2013.01 - KR US); C21D 2211/008 (2013.01 - KR US)
Designated contracting state (EPC)
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated extension state (EPC)
BA ME
DOCDB simple family (publication)
EP 3715493 A1 20200930; EP 3715493 A4 20201125; CN 111527224 A 20200811; CN 111527224 B 20211105; JP 6562180 B1 20190821; JP WO2019130713 A1 20191226; KR 102416655 B1 20220706; KR 20200093002 A 20200804; MX 2020006763 A 20200824; US 11492677 B2 20221108; US 2021062282 A1 20210304; WO 2019130713 A1 20190704
DOCDB simple family (application)
EP 18895022 A 20181009; CN 201880084272 A 20181009; JP 2018037569 W 20181009; JP 2019504143 A 20181009; KR 20207018283 A 20181009; MX 2020006763 A 20181009; US 201816957739 A 20181009